1. Field of the Invention
The present invention generally relates to electromagnetic radiation control devices. More specifically, the present invention relates to a method and apparatus for configuring and tuning crystals for switching and filtering of electromagnetic radiation.
2. Description of the Related Art
In communications systems using optical multiplexing such as dense wavelength, division multiplexing (DWDM), wavelength division multiplexing (WDM), time division multiplexing (TDM) and the like, the distribution of optical information is facilitated by the use of components such as fiber optic gratings, interferometers, various types of filters and the like. Traditional optical components, which are fabricated in plastic, semiconductor, or glass, are largely fixed in their optical properties by their rigid, essentially permanent structures. Thus, in this context, the distribution of optical information is also fixed and the service provider is unable to change the configuration of the DWDM, WDM or TDM format, e.g., distribution, without physically changing the communications system.
One type of photonic crystal known in the art comprises a glass or semiconductor substrate having a plurality of cylindrical apertures formed therethrough in a pattern. Some or all of the cylindrical apertures, such as pillars can be filled with a material having a refractive index different from the refractive index of the substrate.
As light is injected into one end of the substrate, the light interacts with the pillars. The light, as it propagates through the crystal, will be split into multiple paths that constructively and deconstructively interfere with one another to effectively filter the light as it passes through the crystal. For example, a particular bandwidth of light propagates through the filter and other wavelengths of light are either reflected or absorbed within the crystal structure. Generally, the spacing of the pillars and their refractive indices defines a filter that reflects a certain bandwidth of wavelengths of light. The pillars may be filled with gas, fluid or solid materials having various refractive indices. Crystal structures of this type are formed for a specific use and filter a specific wavelength of light and are not reconfigurable in a selective manner. As such, the crystals are used in applications where a fixed filter is necessary or desired.
Therefore there is a need in the art for a method and apparatus for configuring and tuning a photonic crystal.
The present invention is a method and apparatus for configuring and tuning a crystal by selectively controlling a fluid supplied to a plurality of nodes formed in a substrate. The apparatus comprises a substrate having at least one node that can be selectively supplied with a fluid that changes a material property of the node. The material property may include refractive index, magnetic permeability, inducible refractive index, absorption and the like. The node may be a spherical cavity in a three-dimensional structure, a cylindrical aperture in a two-dimensional structure, or a cavity in a one-dimensional structure. The node or nodes within the substrate are coupled to a fluid distribution assembly that selectively alters the material property of the node(s). The material property may be changed by moving the fluid, or a material in a fluid, using electrohydrodynamic pumping, electroosmotic pumping, electrophoresis, thermocapillarity, electrowetting or electrocapillarity. Such crystal structures can be used to switch or filter electromagnetic radiation such as light or microwaves.